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    <title>Document</title>
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    <script>
        function reverse(arr) {
            if (arr instanceof Array) {
                var newArr = [];
                for (var i = arr.length - 1; i >= 0; i--) {
                    newArr[newArr.length] = arr[i];
                }
                return newArr;
            } else {
                return 'error 这个参数要求必须是数组格式 [1,2,3]'
            }

        }
        var arr1 = reverse([9, 8, 7, 6, 5, 4, 3, 2, 1]);
        console.log(arr1);
        var arr2 = reverse(['red', 'green', 'pink', 'hotred', 'blue']);
        console.log(arr2);
        console.log(reverse(1, 2, 3));
        var obj = {};
        console.log(Array.isArray(obj));
    </script>
</body>

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